Percutaneous interventional procedures to treat occlusive vascular disease, such as angioplasty, atherectomy, and stenting, often dislodge material from the vessel walls. This dislodged material, known as emboli, enters the bloodstream and may be large enough to occlude smaller downstream vessels, potentially blocking blood flow to tissue. The resulting ischemia poses a serious threat to the health or life of a patient if the blockage occurs in critical tissue, such as the heart, lungs, or brain.
The deployment of stents and stent-grafts to treat vascular disease, such as aneurysms, involves the introduction of foreign objects into the bloodstream, and also may result in the formation of clots or release of emboli. Such particulate matter, if released into the bloodstream, also may cause infarction or stroke.
Numerous blood filters are known that are designed to capture material liberated from vessel walls during the treatment of vascular disease. Such treatment procedures, such as angioplasty, atherectomy and stenting, typically involve transluminally inserting an interventional device to the treatment site along a guidewire. Upon completion of the procedure, the interventional device is removed from the patient's blood vessel, and a retrieval mechanism, such as a sheath, is advanced along the guidewire in order to retrieve the blood filter.
One drawback associated with using a sheath to retrieve a filter is that the retrieval process requires two steps: (1) the interventional device (e.g., angioplasty catheter) must be removed and (2) the retrieval sheath must then be advanced along the guidewire to retrieve the filter. This additional exchange adds time to the length of the procedure, involves introduction of an additional element (the retrieval catheter) into the patient's vasculature, and enhances the risk of dislodging the filter and permitting emboli to escape therefrom.
Moreover, as the retrieval sheath is advanced along the guidewire, its distal end may become entangled with a stent disposed within the patient's vessel. If, for example, a stent has been deployed, the distal end of the retrieval sheath may inadvertently engage a stent strut, preventing further advancement of the retrieval sheath within the vessel, or even possibly causing vessel dissection.
One disadvantage associated with attempting to retrieve a vascular filter using the guidewire lumen of an interventional device, such as an angioplasty catheter, is that the diameters of such lumens are typically quite small, e.g., 0.014 inch. Accordingly, it is not possible to retrieve previously known vascular filters using the guidewire lumens of most interventional devices.
In view of the foregoing, it would be desirable to provide improved apparatus and methods that streamline retrieval of a vascular filter.
It further would be desirable to provide improved apparatus and methods that facilitate retrieval of a vascular filter, with reduced risk of entangling a retrieval sheath in a deployed stent.